E is for Ecstasy by Nicholas Saunders

Appendix 1: Reference Section

Review of papers to 1993. Makes the point that most fatalities in England
were not among first time users, so it is likely that death was due to the
conditions of use rather than individual susceptibility as has been
suggested by Henry in Toxicity and Deaths from MDMA and Larner in a letter
to The Lancet. In Australia the use of E at raves has been widespread
without any reported problems. This may be due to variations in purity,
ventilation, reporting or simply extent of use.

Direct attribution to MDMA in reported cases of psychiatric disturbance due
to Ecstasy is questionable due to additional factors such as other drugs
and previous vulnerability to psychiatric disturbance. However, two cases
in Italy and one in South Africa imply that no other factors were involved.
There may be particularly susceptible individuals.

"Large doses (acute or cumulative), history of psychiatric disturbance and
preexisting disease appear to increase the likelihood of adverse effects."